Method and means for controlling the exhaust of internal-combustion engines



June 12, 1928. 1,673,414

H. H. MAXlM METHOD AND MEANS FOR CONTROLLING THE EXHAUST OF INTERNAL COMBUSTION ENGINES Filed June 30, 1925 I N V EN TOR.

BY 7 M A TTORNEYS.

Patented June 12, 1928.

UNITED STATES 1,673,414 PATENT OFFICE.

HIRAM HAMILTON MAXIM, F HARTFORD, CONNECTICUT, ASSIGNOR TO THE MAXIM SILENCER COMPANY, OF HARTFORD NECTICUT.

CONNECTICUT, A CORPORATION OF CON- METHOD AND MEANS FOR CONTROLLING THE EXHAUST OF INTERNAL-COMBUSTION ENGINES.

Application filed June 30, 1925.

more particularly the modifying of the expressure in t haust pressures in a manner to contribute to a more efficient and uniform operation of the engine.

It has been ascertained that the exhaust discharge from an explosive engine is not, as is commonly supposed, in the form of a single pressure wave of gradually diminish ing intensity particularly when the discharge takes place into'a conduit of any appreciable length as is the usual practice. On the contrary, the exhaust. discharge is in the-form of rapidly oscillating pressures or pulsations, the frequency of which is determined by the form, area and length of. the: discharge conduit. Since the exhaust discharge results in a Wave of alternating high, and low pressure and since the frequency of the same is such that several alternations of pressure occur during the comparatively short period, of the exhaust port opening, it frequently happens that the dimensions of the exhaust conduit are such as to cause a high pressure period in the wave to coincide with the closing of the exhaust port of the engine. This is more prevalent in exhausts of two cycle engines since theduration of the exhaust port opening period is comparatively short and the exhaust gases are expelled with great suddenness and force. Such a result obviously lessens the power eificiency of an engine since far less scavenging of the cylin er takes lace during a period of high e exhaust conduit than would take place during a period of low pressure.

In order to modify and control this oscillatory tendency of such an exhaust so as to insure that the exhaust port closing will coincide with a low pressure period, I propose to impose a load upon the exhaust discharge in a manner which will rapidly dampen the oscillations Without creating back pressure upon the engine, and so designed that the inertia elfect'of the load thus imposed may be adjusted to bring about a condition of pressure as low and erhaps lower than that of atmosphere at t e exhaust port at the time of its closing.

To this end, I provide in the exhaust conduit and at a point closely adjacent to the Serial No. 40,858.

exhaust port, anaspirating opening with access through a passageway to the surrounding atmosphere whereby the hi h velocity exhaust gases passin throug the conduit will draw in or suc throu h said opemng a quantity of air in somew at the same manner as an injector. Such a load upon the high velocity exhaust gases will quickly dampen any pressure oscillations therein, and if the aspirating action is made totake effect through a passageway of proper form and dimensions, the inertia of the body of air therein immediately acted upon will cause a. low pressure condition at the, exhaust port quickly following the. initial high pressure of the discharge, which low. pressure condition may be timed to coincide with exhaust port closing. For this purpose, my asp rating opening communicates with a passageway of adjustable length and open to atmosphere at its outer end.

Since it is generally desirable to prevent the escape of the exhaust sound through the aspirating opening, the pasageway may conveniently be of tortuous form suited for mufiling sound in accordance with well known silencing principles. .In other words, by mounting a silencer of suitable design over the aspirating opening, it will be possible both to modify the exhaust pressure wave for contributing to a more eflicient operation of the engine as well as to muiiie or silence the sound of the exhaust at said point. Of course, only a portion of the exhaust noise will tend to escape at the aspirating opening and if all sound from the exhaust is to be tfilieted, some silencer of standard desi n s ould be connected to the outlet of the mam exhaust conduit.

Havin described in general the aim and object o the invention, a suitable construction for carrying out the same will now be more particular y described in connection with the accompanying drawings, which show a preferred embodiment thereof.

Fig. 1 is a view in elevation of an internal combustion engine with exhaust discharge conduit leading therefrom showing the principal features of the invention in section;

Fig. 2 is a section through discharge conduit and silencer along line 2-2 of Fig. 1.

Referring more particularl to the drawings, 1 indicates the cylinder block ofan internal combustion engine of any suitable type, which may for example be of the two cycle type having an exhaust port uncovered by a piston. 2 is the base or crank case of said engine. 3 indicates a short length of pipe which functions like an injector nozzle leading from the exhaust port of the engine and extending a short distance into a slightly larger pipe 4, which latter serves as the exhaust conduit for the engine.

The exhaust conduit 4 is preferably secured to the side of the engine as shown, and at a proximate point rearwardly of the front open end of pipe 3 is provided with an aspirating opening 5 which communicates with p the inner end of a tortous or spiral assageof the spiral scroll type'a-nd compriseshead indicated genera y at 7. The annular space between pipes 3 and 4 leadin backwardly from the front open end of saif pipe 3 to the opening 5 is designed so that the high velocity gases issuing from pipe 3 into pipe 4 will cause an aspirating action through opening 5 and passagieway 6 of the silencer from the open atmosp ere. The silencer 7 in the present embodiment is way 6 in a silencer,

er plates 8 and 9 with a spirally arranged partition 10 extending therebetween so as to provide in said silencer the passageway 6, as

shown in Fig. 2. The inner end of said passageway 6 coincides with the opening 5 in pipe 4 and the outer end is near the periphery of said silencer at 11 for communication with an annular passage open to the atmosphere at 13 and serving as the inlet for said aspirating passageway 6. The header 8 is slightly larger in diameter than header 9 and extending from one side of header 8 and spaced from the scroll 10 is a cylindrical casing 12 whereby the annular inlet passage 13 for said silencer is provided between said casing and the scroll 10.

In order to vary the inertia effect ofthe body of air contained in the spiral passageway 6 when acted upon by the injector nozzle 3 and thus insure a condition of low pressure at the exhaust port at the proper time for coinciding with the exhaustport closing, the spiral passageway 6 is made adjustable in length. For this purpose, there is mounted a parti-cylindrical plate 14 upon the outermost portion of the scroll 10 so as to overlap the same as shown in Fig. 2. The member 14 may be moved circularly around the scroll 10 so as to in effect extend the outer end of the same and adjust the length of said passageway 6. When the end 15 of the member 14 is carried to the point 16 on scroll 10, the opening at 11 will be entirely closed and thus access to the atmosphere through opening 5 will be also closed. The member 14 may be given its adjustable movement in any suitable manner and, as shown, there is provided at one side thereof a supporting spider frame having a bearing sleeve 17 rotatably mounted on pipe 4 and carryin a gear '18 operable through bevel gear 19 an crank 20. A collar 21 fixed to pipe 4 serves to retain the parts in position. Adjacent the outlet end of the conduit pipe 4 is preferably mounted a silencer 25 of any standard design, whereby the main sound from the exhaust will be muflied or eliminated.-

. The operation of the device may be described as follows: Upon each opening of the exhaust port of the engine, the exhaust gases will emerge with high velocity-from the end of injector nozzle 3 into the discharge conduit 4. This will set up a strong aspirating or sucking action through the opening 5 upon the column of air partially confined within the spiral passageway 6. Much of the energy from the discharge exhaust will thus be expended in setting in motion the column of air in passageway 6 and this loss of energy will effectively and quickly dampen the tendency toward oscillatory pressure in the exhaust. The inertia efiect of passageway 6 when once started in motion by the aspirating action will react upon the the column of air within the end of nozzle 3 for lowering the pressure thereat and at the exhaust port, immediately after the initial high pressure wave from the exhaust. This, condition of low pressure at the exhaust port may be .properly timed by varying the inertia efiect from the column of air in done by adjusting the ength of said passage way as described and thus a period of low pressure may be made to coincide with the closing of the exhaust port. By the proper adjustments, the reaction from the inertia effect of the air within passageway 6 may be such as to carry the pressure at the exhaust port even below that of atmosphere as is desirable for the most efficient operation of the engine. In addition to thus modifyin the exhaust pressures, the device describe will effectively dissipate sound waves and furnish substantially noiseless operation.

It is to be understood that various changes in details and arrangements of the parts as shown may be made without departing from the scope and spirit of the mventlon as hereinafter claimed.

I claim:

1. The combination with an internal combustion engine of means for rapidly damping pressure pulsations in the explosive "discharge of gases through a conduit leading from the exhaust port of said engine, comprising an exhaust conduit having an aspirating opening located closely adjacent said port, a silencer at said opening to prevent the escape of the sound of the exhaust therethrough, said silencer being provided with an adjustable passageway for the passage of air to 'said opening.

2. The combination with an internal com passageway 6 which is hustion engine of means for rapidly damping pressure pulsations in the explosive dis charge of gases through a conduit leading from the exhaust port of said engine, comprising an exhaust conduit having an aspirating opening located closely ad'acent said port, an injector nozzle from sai port leading into said exhaust conduit, a silencer at said opening to prevent the escape of the sound of the exhaust therethrough, said silencer being provided with a spiral passageway for the passage of air to said open ing, and means for adjusting the length of said spiral passageway.

3. The combination with an internal combustion engine havin an exhaust port of means for causing t e exhaust discharge from said port to produce an aspirating action comprising an exhaust conduit havin an aspirating opening located closely adacent said port, a. tortuous passageway leading from said opening to atmosphere of suflicient length to substantially muflle the sound from the exhaust at said opening, an aspirating nozzle from said exhaust port leading into said exhaust conduit, the outlet of said nozzle being located in proximity to said apirating opening, and means vfor adjusting the length of said tortuous passa eway.

n testimony whereof I have aflixed my signature.

HJBAM HAMILTON MAXIM. 

